remove unused HWC_BLIT from enum

Change-Id: I5d2a66292ba8c6b1fc0ad44b4922859c1a18a9d2
fix graphic artifacts when rotating

Change-Id: I69785853517004d45ed57d84714a104e4dbd111a
update comments from cm-11 hwcomposer.h

Change-Id: I7b7d1e502210658fbe89a22884a425d66a5a9f60